Creating a RS232 X-Windows terminal?

Creating a RS232 X-Windows terminal?

Post by Andreas Koc » Mon, 29 Apr 2002 20:20:00



(f'up to comp.os.linux.x set)

Hi,

with my limited *nix knowledge and time this question is
pretty hypothetical, but...

Would it be possible/how much work would it be to
create a X-windows terminal out of a PDA ?

It is possible to do a text terminal emulation like VT100
using a PDA with terminal app and linux.

Now,
-can linux use a X-Server (the thing that displays is the
  server, and the apps are clients, if i got the methodology
  right) connected over a serial (RS232) line?
-if yes, can it use a "raw" protocol (or does it need a TCP
  connection)
-how complex is the protocoll/X-Server app?
  Can it be ported to an obviously limited system?
-Would a x-server with a pretty low resolution
  (down to 160*160 in 4 greyscales on  a palm, but we could
   interpolate to 320*320 mono...) be actually usefull?

Is there allready some non-commercial solution to this
issue?

--
                                                   Andreas
if ((sex==fem)&&(hobby==comp)&&(age~25)&&(status==single)
&&(cntry=GER)) goto http://www.kochandreas.com/home/single.htm

 
 
 

Creating a RS232 X-Windows terminal?

Post by Norman Levi » Tue, 30 Apr 2002 04:05:35


An xwindow terminal?  Why not start of small.  I did see a user with a palm, a
serial cable hook up to tty0 and use it as a vt100.  I do NOT know the emulation
program - but lets not go crazy and want graphics on the pda.
norm


| (f'up to comp.os.linux.x set)
|
| Hi,
|
| with my limited *nix knowledge and time this question is
| pretty hypothetical, but...
|
| Would it be possible/how much work would it be to
| create a X-windows terminal out of a PDA ?
|
| It is possible to do a text terminal emulation like VT100
| using a PDA with terminal app and linux.
|
| Now,
| -can linux use a X-Server (the thing that displays is the
|   server, and the apps are clients, if i got the methodology
|   right) connected over a serial (RS232) line?
| -if yes, can it use a "raw" protocol (or does it need a TCP
|   connection)
| -how complex is the protocoll/X-Server app?
|   Can it be ported to an obviously limited system?
| -Would a x-server with a pretty low resolution
|   (down to 160*160 in 4 greyscales on  a palm, but we could
|    interpolate to 320*320 mono...) be actually usefull?
|
| Is there allready some non-commercial solution to this
| issue?
|
| --
|                                                    Andreas
| if ((sex==fem)&&(hobby==comp)&&(age~25)&&(status==single)
| &&(cntry=GER)) goto http://www.kochandreas.com/home/single.htm
|

---
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Creating a RS232 X-Windows terminal?

Post by Andreas Koc » Tue, 30 Apr 2002 06:08:43



> An xwindow terminal?  Why not start of small.  I did see a user with a palm, a
> serial cable hook up to tty0 and use it as a vt100.  I do NOT know the emulation
> program - but lets not go crazy and want graphics on the pda.

Well, as you describe - "small" is allready there ;-)

--
                                                   Andreas
if ((sex==fem)&&(hobby==comp)&&(age~25)&&(status==single)
&&(cntry=GER)) goto http://www.kochandreas.com/home/single.htm

 
 
 

Creating a RS232 X-Windows terminal?

Post by Skylar Thompso » Tue, 30 Apr 2002 04:36:47



> (f'up to comp.os.linux.x set)

> Hi,

> with my limited *nix knowledge and time this question is
> pretty hypothetical, but...

> Would it be possible/how much work would it be to
> create a X-windows terminal out of a PDA ?

> It is possible to do a text terminal emulation like VT100
> using a PDA with terminal app and linux.

> Now,
> -can linux use a X-Server (the thing that displays is the
>   server, and the apps are clients, if i got the methodology
>   right) connected over a serial (RS232) line?
> -if yes, can it use a "raw" protocol (or does it need a TCP
>   connection)
> -how complex is the protocoll/X-Server app?
>   Can it be ported to an obviously limited system?
> -Would a x-server with a pretty low resolution
>   (down to 160*160 in 4 greyscales on  a palm, but we could
>    interpolate to 320*320 mono...) be actually usefull?

> Is there allready some non-commercial solution to this
> issue?

If you're limited to RS232, I wouldn't even try. Serial cables have a
maximum bandwidth of 115kb/s (23kB/s) and a latency of about 0.1s. XDMCP is
generally run over Cat3 or Cat5 cabling with at least 100 times the
bandwidth and a tenth the latency. To achieve liveable performance, you
need about 1Mb/s and 0.05s latency.

--

 
 
 

Creating a RS232 X-Windows terminal?

Post by Remc » Tue, 30 Apr 2002 16:50:49



> Would it be possible/how much work would it be to
> create a X-windows terminal out of a PDA ?

I guess your question is whether there is an X-server running on
PalmOS. Try google. With the same google it is possible to find that
there is VNC client running under PalmOS. So you can run a VNC server
on your UNIX box and have your Palm connect to it.

If you are looking for a project then I guess it would be a fun
project and certainly doable. I would start by checking out the source
of the java X-servers. The X-protocol itself is not very difficult,
On problem is which extensions to support and how. You can find all
info on the X-protocol on the XFree86 website or on www.x.org.

R.

 
 
 

Creating a RS232 X-Windows terminal?

Post by Skylar Thompso » Tue, 30 Apr 2002 19:45:17




>>If you're limited to RS232, I wouldn't even try. Serial cables have a
>>maximum bandwidth of 115kb/s (23kB/s)

> The cables are not the problem as long as they are not too long and of
> decent quality. It's the clock speed of the UARTs on standard
> motherboards or cheap serial boards that limits the bandwidth.

> Most modern modems support up to 230kb/s and some (e.g. the Zyxel 2864
> series) even 460kb/s. Still not very much but at least enough for
> European ISDN with channel bundling.

460kb/s is still less than 60kB/s. Performance on an X server is going to
be fairly jerky.

--

 
 
 

Creating a RS232 X-Windows terminal?

Post by Andreas Koc » Wed, 01 May 2002 06:10:40



> If you're limited to RS232, I wouldn't even try. Serial cables have a
> maximum bandwidth of 115kb/s (23kB/s) and a latency of about 0.1s. XDMCP is
> generally run over Cat3 or Cat5 cabling with at least 100 times the
> bandwidth and a tenth the latency. To achieve liveable performance, you
> need about 1Mb/s and 0.05s latency.

Probably depends on what performance you need - taking into account

that you will have something like a 1" screen with 160*160 pixels
and no keyboard, no one will use this for intensive working.

About how much m(?)s latency are we speaking for something like 9600
baud?

--
                                                   Andreas
if ((sex==fem)&&(hobby==comp)&&(age~25)&&(status==single)
&&(cntry=GER)) goto http://www.kochandreas.com/home/single.htm

 
 
 

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